Method for working up roasted pyrites containing copper and zinc



Patented Feb. 23, .1932

No Drawing. Application filed .Tuly 2 2, 1931, Serial No. 552,538, and in Germany August 31, 1928.

The invention relates to a. method for working up roasted pyrites containing copper and zinc which have been subjected to chloridizing roasting, by treating the roasted material with leaching liquids.

It is already known that by fractional treat ment of such material with leaching liquid as, for instance, pure water or slightly acidified water from the wash towers for the exhaust gas of the roasting furnaces, it is possible to obtain the greater part of the leachable zinc in the first liquor fraction and the greater part of the leachable copper in the second liquor fraction. The leaching is accomplished in the ordinary way by the so-called trickling leaching", in which the roasted material is placed in a layer of about 1.5 meters in height on a grate-like supportin large receptacles with inclined floors and an outlet opening at the lowest part of the floor, and is then covered with the leaching liquid. The liquor flowing down is collected in fractions, whereupon each of the separate liquor fractions is worked up by itself.

This working-up and recovery of the zinc, on the one hand. and the copper, on the other hand, from the liquor fractions obtained in this way is accomplished the more simply and satisfactorily the less the content of copper in thezinc fraction and the content of zinc in the copper fraction. The invention depends on the discovery that an exceedingly t orough separation of these constituents can be produced by the fractional leaching if the leaching operation is carried out at such low temperatures that the temperature of the first liquor fraction flowing 0 outlet, at the maximum does not greatly exceed (3., and if for this purpose the roasted material coming from the furnace is subjected before the leaching to a cooling sufficiently thorough that its temperature is less than 80 C. and preferably not more than about 70 C. after it is charged into the 1eaching vat and before the addition of the leaching liquor.

At present the roasted material comin from the furnace is generally subjected to the following treatment before leaching: The

still highly, heated material spread out in if, measured at the thin layers on a movable surface, for instance on a rotary heated roasted uid The disadvantages thus and excessive consumption of the leaching liquid. By this method the cooling of the hot From this point downward, however, a further considerable cooling of the material according to this process, by direct supply of water, is no longer feasible, since the material cannot take up more than 842% water at the most, without conversion to a pasty paste.

Such a thorough cooling of the roasted material as is necessary forproducin a leaching temperature not exceeding 50- 70 C., desired in theinvention, and a corres-- ponding thorough separation of the zinc ing of the material would occur at temperatures the avoidance of which is exactly the purpose of the present invention,'in addition to the above-mentioned disadvantages.

A sutlicient cooling effect is on the contrary produced according to the invention by subjecting the material coming from the furnace or precooled by the known method by direct spraying with water, to a further cooling with avoidance of direct supply of liquid,

preferably adirect cooling by circulated air.

ndirect cooling with coolin liquid can also be used for this purpose; or instance, the 5 material can be sent through pipes or shakingconveyors externally cooled by water.

In certain cases two or more of these cooling processes can be used simultaneously or successively; For t e leaching,

- made for instance of the acidulous liquid obtained in the washing of the acid exhaust gases of the roasting process. It has been ound advisableto cool the leaching liquid before the action on the roasted material.

In order to avoid the harmful separation of Glaubers salt in the roasted material during the leaching operation, it is generally advisable not to carry ed materialand/or of the cooling liquid so far that the temperature of themixture of roasted material and liquor goes below 324 C. during the leaching.

By working in the way described it is possibleto carry the separation oi the zinc from copper so far even in that in leaching roasted pyrites having a normal average content of about 1-370 Zn and 1 3% Cu with the usual total volume of liquid of 1 cubic meter to 1 ton of the roaste material, the first liquor fraction, preferably amounting to about 20-30% of the whole amount of liquor, contains about 90% and over of the leachable zinc and only about or a little more of the leachable copper, so that the ratio Zn: Cu in the solution amounts to about 6: 1 to 5 1. According to the rocess heretofore known, it is ossible to 0 tain at the most only about 90 o of the leachable about 35% of the leachable copcorresponding to a zinc with per, .in the first fraction,

ratio of Zn: Cu of only 2.6: 1.

The exceptional advantage produced by the process of the invention resides not only in the increase in zinc output in the first liquor fraction, but above all inthe fact that with the decrease inthe amount of copper going over in the zinc fraction, the separation of the copper from the zinc and the separation of the zinc in nureform is facilitated.

By temperature of the first liquor fraction flowing ofi from the liquor vat in the description and the claims is meant the 55 greatest temperature attained by the first liq- .uor fraction, measured directly at the outlet during the flowing off, when after overcoming an original cooling oii by cold parts,

especially the cold bottom, of the liquor va the temperature of the liquor flowing out has reached its maximum.

B temperature of the roasted material in t e description and in the claims is to understood the average temperature of the difierent layers of the roasted material d1 "examples I tainin besides water, use can be I the coo 'ing of the roastthe fractional leaching py tion of the leaching solution was 85 C. The

leaching solution may 1; iron.

- of application rectl after introduction of the whole material m the liquor vat measured in the middle of the liquor vat and before the addition of the leaching liquid.

The great advantages obtained b vention may be illustrated by the 1 the inollowing 1. 90,000 kg. of roasted pyrite cinders con- 2% of zinc,2%of copper and 9% of humidity were cooled so that the temperature of the roasted material in the leaching vat prior to the application of the leaching liquor -did not exceed 50 C The maximum temperature of the first liquor fraction (25 cubic meters), measured at the outflow, was C. This first fraction contained more than 90% of the leachable zinc and only 15% of the leachable copper. The ratio between zinc and copper was therefore 6:1 in'this fraction.

2. In another experiment made for comparing the new method with the ordinary methods the same amount of the same cinders was leached in the same manner as in example 1, except that the temperature of the roasted rite in the leaching vat prior to introduc- 1 C. This first fraction (25 cubic meters) con tained more than90% of the leachable zinc, but 45% of the leachable cop er. The ratio between-zinc and cop or was t erefore 2: 1.

The two comparative tests show the great advantages obtained by operating according to the invention. They show, however, also that even temperatures of the leaching solution not much above lead to far greater amounts of copper in the first fraction.

The difierent fractions of the leaching solu tion may be worked up according to usual methods. Thus, for example,,the first fraction, called the zinc-fraction, is treated with iron, or, for example, zinc oxide, in order to remove'the copper by cementation or precipitation. Then the Glaubers salt present in the zinc fraction is removed, for example by freezing, and from the remaining solution the zinc is precipitated, for example by treatment with milk of lime. In case the copper has been removed by cementation with iron, it is of advantage to remove amounts of iron which went into solution, according to usual methods, before precipitating the zinc.

The copper in the second fraction of the be recovered in known manner, for example by cementation with This application is a continuation-in-part Serial No. 317 ,473, filed Nov. 5, 1928.

We claim: 7 c v 1. A method for working up copper-. and zinc-containing roasted pyrites which have the small mean:

been subjected to chloridizing roasting, which comprises fractionally leaching the roasted material after it has been cooled to such a temperature that the first leaching fraction has when flowing off a temperature not substantially above 50 C., whereby the first leaching fraction contams substantially all he zinc contained in the roasted material, and the subseqpent fraction contains substantially all of the copper contained in the roasted material.

2. A method for working up 'copperand zinc-containing roasted pyrites which have been subjected to chloridizing roasting, which comprises fractionally leaching the roasted he subsequent fraction contains substantially all of the copper contained in the roasted material.

3. A method for working up co zinc-containing roasted pyrites w ich have roasted material, and the subsequent fraction contains substantially all of the copper contained in the roasted material.

4. A method for working up copperand zinc-containing roasted pyrites which have been subjected to chloridizing roasting,

' which comprises fractionally leaching the roasted material after it has been cooled at least partly without direct contact with the leaching liquor to such a temperature that the first eaching fraction has when flowing off a temperature not substantially above C., the first leaching being carried out with cooled liquor, whereby the first leaching fraction contains substantially all of the f 21110 contained in the roasted material, and the subsequent fraction contains substantially all of the copper contained in the roasted material.

5. A method for working up copperand zinc-containing roasted pyrites which have been subjected to chloridizing roasting ich comprises fractionally leaching the roasted material after temperature of about 100 (1. down to such a temperature that the first leaching fraction has when flowing oil a temperature not substantially above 50 C,

whereby the first leaching fraction contains G substantially all of the zinc contained in the perand d g tional leaching,

roastedmaterial, and the subsequent fraction contains substantially all of the copper contained in the roasted material.

Process of workmg up roasted pyrites I thereafter subjecting the material to fracfraction contains substantially all of the zinc contained in the roasted material, and t e subsequent fraction contains substantially all of the copper contained in the roasted material.

8. rocess. of working up roasted pyrites containing copper and zinc which have been subjected to chloridizing roasting, comprises first precooling the roasted maerial after leavi g the furnace,

temperature, measured as an erent layers in the middle thereafter tional leaching, whereby the raction contains substantially all of the zinc contained in t e roasted material, and the subsequent fraction contains substantially all of the copper contained in the roasted material. a

9. Process of working up roasted pyrites containi g copper and subjecte first leaching I b aftlelar part t e contact there ith and without direct contact with liquid, to such an extent that its temperature, measured as an average of the dlflerent layers in the middle of the leachin vat, is less than 80 and thereafter su jecting the material to fractional leaching, whereby the first leaching fraction contains substantially all of the zinc contained in the roasted material, and the subsequent fraction contains substantially all of the copper contained in the roasted material. V

In testimony whereof, we afiix dur signa tures.

CONWAY, BARON von cmsswALn; f

HANS- wsmmnu. 

